Missing flood seals at TMI might lead to additional inspections

Three Mile Island could face additional federal inspections stemming from an apparent violation that involved missing seals needed to protect the Dauphin County plant against a major flood.

Last August, both TMI and U.S. Nuclear Regulatory Commission officials discovered couplings on electrical cable conduits were missing flood seals, said Ralph DeSantis, a spokesman for TMI.

For at least the past two years, TMI has worked to enhance its flood protection systems. It was during these efforts that the issue with the missing seals were found, he said. "We found that these seals were not there," DeSantis said.

The missing seals would have led to the flooding of plant safety-related equipment and various emergency core cooling systems only if TMI was involved in a flood that was worse than any on record, according to an NRC report issued Thursday.

The flood waters wrought by Tropical Storm Agnes in 1972 stands as a benchmark for what the NRC defines as a probable maximum flood, DeSantis said.

In addition, the plant would have shut down if the Susquehanna River had approached Tropical Storm Agnes flood levels, DeSantis said.

"The river doesn't flood that quickly," he said. "It would have taken days and days to reach the probable maximum flood level. There was no threat to the nuclear safety of TMI."

During its review of the apparent violation, the NRC found that the missing seals did not present "an immediate safety concern," according to a federal report.

Still, based on the fact that the plant did not promptly identify and correct the violation, the NRC issued TMI a preliminary "white" finding. That type of finding represents an issue of low-to moderate-safety significance that might lead to additional NRC oversight.

Plant officials do not plan to request a regulatory conference, essentially relinquishing its right to appeal the commission's final determination of the finding, DeSantis said.

Since the discovery of the missing seals, the plant has taken both temporary and permanent corrective actions. In August, the plant immediately staged sand and large-earth moving equipment to protect against flooding.

In October, the plant sealed the conduits with watertight material -- a repair that met the requirements of the NRC, according to a federal report.

"When we found it, we took action right away so that we could secure that area from floods," DeSantis said.